Multiplex Control Unit Input Tests (Civic)
- Remove driver's dashboard lower cover. Unplug underdash fuse/relay box connectors "B", "G", "J", "X" and "Y". See Fig 1. Inspect connector terminals for damage or corrosion. Repair as necessary and retest system. If connector and terminals are okay, go to next step.
- Using DVOM, perform control unit input test. See Fig 1. If an input test indicates a problem, find and correct cause and retest system. If all input test results are okay, multiplex control unit is faulty. Replace underdash fuse/relay box assembly.
Courtesy of AMERICAN HONDA MOTOR CO., INC.